Here's what I think happened with Cody last year. It was an unfortunate combination of circumstances:
1) Cody wasn't physically ready for the NBA. He was getting pushed around, wasn't able to keep his line, had a hard time keeping control of the ball, had a hard time rebounding, etc. due to a lack of strength. He needs to put serious work in on his body and adjusting to the physicality of the NBA. Showing up at 178 lbs instead of 190 lbs set him back another year, basically.
2) Cody can only score in certain situations, and those aren't the situations that the Jazz want to put him in. For example, Cody is comfortable with an 18-ft jumper above the foul line. He's comfortable with drives where he gets all the way to the rim or can finish with a short floater. He's not going to get those opportunities for a while.
3) The combination of the above made him historically ineffective and passive on offense. Cody would go several minutes and multiple possessions without touching the ball. For a guy who is used to having the ball and making decisions, he didn't get rhythm or confidence. Coaches would occasionally feed him an opportunity or two coming out of halftime where he had been shooting and warming up.
The Good News, if there is any...
1) If Cody can improve his body--strength, stamina, burst, etc.--he can still become an NBA athlete in another year or two.
2) If Cody learns to score from where the coaches want him to be on the floor--e.g., the NBA 3pt line, further out on his floaters, angle midrange off the dribble--he can still contribute offensively, along with a few of his slippery drives to the rim. Presumably, Cody has been taking a ton of shots everyday.
3) Cody moves really well defensively and can track 2s and 3s. He also sees the floor and makes good passes at game speed. His problem with staying engaged can be solved by improving his body and improving his shooting from where the Jazz want him on the floor. He's going to need to make himself a role player in the mold of Jaden McDaniels, who incidentally also took a few years to become a solid contributor.